<!--
 * @Author: yaojian66 1327629137@qq.com
 * @Date: 2022-06-23 15:29:54
 * @LastEditors: yaojian66 1327629137@qq.com
 * @LastEditTime: 2022-06-23 16:04:35
 * @FilePath: \geyao\第二十一题 css单位一.html
 * @Description: 这是默认设置,请设置`customMade`, 打开koroFileHeader查看配置 进行设置: https://github.com/OBKoro1/koro1FileHeader/wiki/%E9%85%8D%E7%BD%AE
-->
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>css单位1</title>
  <style type="text/css">
    .box {
        /*补全代码*/
        width:4em; 
        height:4em;
    }
</style>
</head>
<body>
  <!-- 请将html模块中类为"box"的div元素的宽度和高度设置为自身字体大小的4倍。 -->
  <div class='box'></div>
</body>
</html>